The present invention generally relates to firearms, and more particularly to an improved device suitable for use with, but not limited to rimfire-type cartridges to indicate the presence of a cartridge in the chamber of a pistol (i.e., a “loaded chamber”).
While the loaded condition of a firearm's chamber is customarily and most positively checked by the user opening the action and visually observing the presence of a cartridge therein, there have been prior devices which attempt to augment this procedure by providing a mechanical device to signal the chamber's state of readiness, particularly in military firearms where opening the chamber and observing the loaded condition of same may not be practical or possible due to the need for stealth. In a known loaded chamber indicator, an opening or window is cut into the rear portion of the barrel or chamber wall. The opening extends radially inwards from the side of the barrel and through the barrel's rear face against which the rim of a cartridge abuts when a cartridge is loaded into the barrel bore. An elongated thin elastic clip is provided that is fixed to the front portion of the barrel at one end. At the opposite end, the clip has a small projection that protrudes through the window in the barrel to contact the side of the cartridge casing when a cartridge is loaded into the barrel. The clip, however, is physically deflected outwards only by a very small amount by the cartridge casing. Moreover, the clip does not protrude beyond the exterior surface of the pistol in a loaded chamber condition, making the indicator not readily noticeable. Both of these factors make it difficult for a pistol user to visually distinguish a loaded chamber condition from an empty chamber condition by use of such devices.
In another known indicator; a very small viewing window or port is similarly cut into in the barrel or chamber wall of a pistol to allow the presence of the cartridge casing in the barrel bore to be seen through the window. Dirt, unburned gun powder residue, carbon build-up, and grease may obscure the small viewing ports and render them ineffective. The viewing port type indicators are also not useable at night or in other darkened environments.
A drawback of the foregoing known loaded chamber indicators is that they are also not suitable for use with all types of known self-contained cartridges currently on the market today because the window cutouts in the rear barrel or chamber reduce structural support of the cartridge casing and rim. In particular, the foregoing indicators are not well-suited for the very popular rimfire-type cartridges, such as the .22 Long Rifle, which optimally require substantial structural support of the cartridge casing and rim during firing. In a rimfire cartridge, the impact-sensitive primer material, which is used to ignite the propellant powder (i.e., gunpowder), is distributed inside and around the base of the cartridge casing in the rim. The rim is a relatively thin and narrow laterally-protruding hollow annular structure disposed around the circumference of the cartridge casing at its base. An annular space is contained inside the rim for holding the primer material. Striking the rim from the rear (such as with a firing pin) crushes and flattens the rim together against the rear face of the barrel or chamber. This “squeezing” deformation of the rim creates internal friction in the primer material sandwiched in the narrow annular space within the rim, and ignites the primer which in turn sets off the propellant powder. Accordingly, the casing in the base area, and in particular the rim of the cartridge casing, are intentionally made relatively thin and weak by structural design to be readily deformable. Therefore, a rimfire-type pistol, to provide maximum support to the base and rim of the cartridge to prevent the fragile rimfire casing from bursting during firing, should preferably not contain cutouts in the barrel or chamber area.
The known loaded chamber indicators discussed above all require cutting away of cartridge support provided by the barrel or chamber to allow those indicators to function properly. There has never been a loaded chamber indicator in the prior art that functions in a truly satisfactory fashion on firearms chambered for rimfire-type ammunition, which comprise a large percentage of the firearms sold. Accordingly, there is a need for a loaded chamber indicator that does not undermine support of a cartridge during firing and, in particular, one which functions satisfactorily with rimfire-type ammunition such as the .22 Long Rifle.